ivi-shell: rework remove_layer notification

The add_notification_remove_layer API accepts a simple
wl_listener instead of a ivi-shell specific notification
function. Therefore, the API is renamed to add_listener_remove_layer.

This change has several advantages:
1. Code cleanup
2. No dynamic memory allocation. Listeners are allocated
   by controller plugins
3. Remove API is not needed. Controller plugins can easily
   remove the listener link.

The remove API is removed too:
- ivi_layout_remove_notification_remove_layer

Signed-off-by: Emre Ucan <eucan@de.adit-jv.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/ivi-shell/ivi-layout.c b/ivi-shell/ivi-layout.c
index a81213a..82a6d55 100644
--- a/ivi-shell/ivi-layout.c
+++ b/ivi-shell/ivi-layout.c
@@ -931,23 +931,6 @@
 }
 
 static void
-layer_removed(struct wl_listener *listener, void *data)
-{
-	struct ivi_layout_layer *ivilayer = data;
-
-	struct listener_layout_notification *notification =
-		container_of(listener,
-			     struct listener_layout_notification,
-			     listener);
-
-	struct ivi_layout_notification_callback *removed_callback =
-		notification->userdata;
-
-	((layer_remove_notification_func)removed_callback->callback)
-		(ivilayer, removed_callback->data);
-}
-
-static void
 surface_removed(struct wl_listener *listener, void *data)
 {
 	struct ivi_layout_surface *ivisurface = data;
@@ -1051,36 +1034,18 @@
 }
 
 static int32_t
-ivi_layout_add_notification_remove_layer(layer_remove_notification_func callback,
-					 void *userdata)
+ivi_layout_add_listener_remove_layer(struct wl_listener *listener)
 {
 	struct ivi_layout *layout = get_instance();
-	struct ivi_layout_notification_callback *removed_callback = NULL;
 
-	if (callback == NULL) {
-		weston_log("ivi_layout_add_notification_remove_layer: invalid argument\n");
+	if (listener == NULL) {
+		weston_log("ivi_layout_add_listener_remove_layer: invalid argument\n");
 		return IVI_FAILED;
 	}
 
-	removed_callback = malloc(sizeof *removed_callback);
-	if (removed_callback == NULL) {
-		weston_log("fails to allocate memory\n");
-		return IVI_FAILED;
-	}
+	wl_signal_add(&layout->layer_notification.removed, listener);
 
-	removed_callback->callback = callback;
-	removed_callback->data = userdata;
-	return add_notification(&layout->layer_notification.removed,
-				layer_removed,
-				removed_callback);
-}
-
-static void
-ivi_layout_remove_notification_remove_layer(layer_remove_notification_func callback,
-					    void *userdata)
-{
-	struct ivi_layout *layout = get_instance();
-	remove_notification(&layout->layer_notification.removed.listener_list, callback, userdata);
+	return IVI_SUCCEEDED;
 }
 
 static int32_t
@@ -2181,8 +2146,7 @@
 	 * layer controller interfaces
 	 */
 	.add_listener_create_layer			= ivi_layout_add_listener_create_layer,
-	.add_notification_remove_layer		= ivi_layout_add_notification_remove_layer,
-	.remove_notification_remove_layer	= ivi_layout_remove_notification_remove_layer,
+	.add_listener_remove_layer		= ivi_layout_add_listener_remove_layer,
 	.layer_create_with_dimension		= ivi_layout_layer_create_with_dimension,
 	.layer_destroy				= ivi_layout_layer_destroy,
 	.get_layers				= ivi_layout_get_layers,